/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.primitives;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;

import java.io.Serializable;
import java.util.AbstractList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.RandomAccess;
import javax.annotation.CheckForNull;

/**
 * Static utility methods pertaining to {@code boolean} primitives, that are not already found in
 * either {@link Boolean} or {@link Arrays}.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
 *
 * @author Kevin Bourrillion
 * @since 1.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class Booleans
{
    private Booleans()
    {
    }

    /**
     * Comparators for {@code Boolean} values.
     */
    private enum BooleanComparator implements Comparator<Boolean>
    {
        TRUE_FIRST(1, "Booleans.trueFirst()"),
        FALSE_FIRST(-1, "Booleans.falseFirst()");

        private final int trueValue;
        private final String toString;

        BooleanComparator(int trueValue, String toString)
        {
            this.trueValue = trueValue;
            this.toString = toString;
        }

        @Override
        public int compare(Boolean a, Boolean b)
        {
            int aVal = a ? trueValue : 0;
            int bVal = b ? trueValue : 0;
            return bVal - aVal;
        }

        @Override
        public String toString()
        {
            return toString;
        }
    }

    /**
     * Returns a {@code Comparator<Boolean>} that sorts {@code true} before {@code false}.
     *
     * <p>This is particularly useful in Java 8+ in combination with {@code Comparators.comparing},
     * e.g. {@code Comparators.comparing(Foo::hasBar, trueFirst())}.
     *
     * @since 21.0
     */
    @Beta
    public static Comparator<Boolean> trueFirst()
    {
        return BooleanComparator.TRUE_FIRST;
    }

    /**
     * Returns a {@code Comparator<Boolean>} that sorts {@code false} before {@code true}.
     *
     * <p>This is particularly useful in Java 8+ in combination with {@code Comparators.comparing},
     * e.g. {@code Comparators.comparing(Foo::hasBar, falseFirst())}.
     *
     * @since 21.0
     */
    @Beta
    public static Comparator<Boolean> falseFirst()
    {
        return BooleanComparator.FALSE_FIRST;
    }

    /**
     * Returns a hash code for {@code value}; equal to the result of invoking {@code ((Boolean)
     * value).hashCode()}.
     *
     * <p><b>Java 8 users:</b> use {@link Boolean#hashCode(boolean)} instead.
     *
     * @param value a primitive {@code boolean} value
     * @return a hash code for the value
     */
    public static int hashCode(boolean value)
    {
        return value ? 1231 : 1237;
    }

    /**
     * Compares the two specified {@code boolean} values in the standard way ({@code false} is
     * considered less than {@code true}). The sign of the value returned is the same as that of
     * {@code ((Boolean) a).compareTo(b)}.
     *
     * <p><b>Note for Java 7 and later:</b> this method should be treated as deprecated; use the
     * equivalent {@link Boolean#compare} method instead.
     *
     * @param a the first {@code boolean} to compare
     * @param b the second {@code boolean} to compare
     * @return a positive number if only {@code a} is {@code true}, a negative number if only {@code
     * b} is true, or zero if {@code a == b}
     */
    public static int compare(boolean a, boolean b)
    {
        return (a == b) ? 0 : (a ? 1 : -1);
    }

    /**
     * Returns {@code true} if {@code target} is present as an element anywhere in {@code array}.
     *
     * <p><b>Note:</b> consider representing the array as a {@link java.util.BitSet} instead,
     * replacing {@code Booleans.contains(array, true)} with {@code !bitSet.isEmpty()} and {@code
     * Booleans.contains(array, false)} with {@code bitSet.nextClearBit(0) == sizeOfBitSet}.
     *
     * @param array  an array of {@code boolean} values, possibly empty
     * @param target a primitive {@code boolean} value
     * @return {@code true} if {@code array[i] == target} for some value of {@code i}
     */
    public static boolean contains(boolean[] array, boolean target)
    {
        for (boolean value : array)
        {
            if (value == target)
            {
                return true;
            }
        }
        return false;
    }

    /**
     * Returns the index of the first appearance of the value {@code target} in {@code array}.
     *
     * <p><b>Note:</b> consider representing the array as a {@link java.util.BitSet} instead, and
     * using {@link java.util.BitSet#nextSetBit(int)} or {@link java.util.BitSet#nextClearBit(int)}.
     *
     * @param array  an array of {@code boolean} values, possibly empty
     * @param target a primitive {@code boolean} value
     * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
     * such index exists.
     */
    public static int indexOf(boolean[] array, boolean target)
    {
        return indexOf(array, target, 0, array.length);
    }

    // TODO(kevinb): consider making this public
    private static int indexOf(boolean[] array, boolean target, int start, int end)
    {
        for (int i = start; i < end; i++)
        {
            if (array[i] == target)
            {
                return i;
            }
        }
        return -1;
    }

    /**
     * Returns the start position of the first occurrence of the specified {@code target} within
     * {@code array}, or {@code -1} if there is no such occurrence.
     *
     * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
     * i, i + target.length)} contains exactly the same elements as {@code target}.
     *
     * @param array  the array to search for the sequence {@code target}
     * @param target the array to search for as a sub-sequence of {@code array}
     */
    public static int indexOf(boolean[] array, boolean[] target)
    {
        checkNotNull(array, "array");
        checkNotNull(target, "target");
        if (target.length == 0)
        {
            return 0;
        }

        outer:
        for (int i = 0; i < array.length - target.length + 1; i++)
        {
            for (int j = 0; j < target.length; j++)
            {
                if (array[i + j] != target[j])
                {
                    continue outer;
                }
            }
            return i;
        }
        return -1;
    }

    /**
     * Returns the index of the last appearance of the value {@code target} in {@code array}.
     *
     * @param array  an array of {@code boolean} values, possibly empty
     * @param target a primitive {@code boolean} value
     * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
     * such index exists.
     */
    public static int lastIndexOf(boolean[] array, boolean target)
    {
        return lastIndexOf(array, target, 0, array.length);
    }

    // TODO(kevinb): consider making this public
    private static int lastIndexOf(boolean[] array, boolean target, int start, int end)
    {
        for (int i = end - 1; i >= start; i--)
        {
            if (array[i] == target)
            {
                return i;
            }
        }
        return -1;
    }

    /**
     * Returns the values from each provided array combined into a single array. For example, {@code
     * concat(new boolean[] {a, b}, new boolean[] {}, new boolean[] {c}} returns the array {@code {a,
     * b, c}}.
     *
     * @param arrays zero or more {@code boolean} arrays
     * @return a single array containing all the values from the source arrays, in order
     */
    public static boolean[] concat(boolean[]... arrays)
    {
        int length = 0;
        for (boolean[] array : arrays)
        {
            length += array.length;
        }
        boolean[] result = new boolean[length];
        int pos = 0;
        for (boolean[] array : arrays)
        {
            System.arraycopy(array, 0, result, pos, array.length);
            pos += array.length;
        }
        return result;
    }

    /**
     * Returns an array containing the same values as {@code array}, but guaranteed to be of a
     * specified minimum length. If {@code array} already has a length of at least {@code minLength},
     * it is returned directly. Otherwise, a new array of size {@code minLength + padding} is
     * returned, containing the values of {@code array}, and zeroes in the remaining places.
     *
     * @param array     the source array
     * @param minLength the minimum length the returned array must guarantee
     * @param padding   an extra amount to "grow" the array by if growth is necessary
     * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
     * minLength}
     * @throws IllegalArgumentException if {@code minLength} or {@code padding} is negative
     */
    public static boolean[] ensureCapacity(boolean[] array, int minLength, int padding)
    {
        checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
        checkArgument(padding >= 0, "Invalid padding: %s", padding);
        return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
    }

    /**
     * Returns a string containing the supplied {@code boolean} values separated by {@code separator}.
     * For example, {@code join("-", false, true, false)} returns the string {@code
     * "false-true-false"}.
     *
     * @param separator the text that should appear between consecutive values in the resulting string
     *                  (but not at the start or end)
     * @param array     an array of {@code boolean} values, possibly empty
     */
    public static String join(String separator, boolean... array)
    {
        checkNotNull(separator);
        if (array.length == 0)
        {
            return "";
        }

        // For pre-sizing a builder, just get the right order of magnitude
        StringBuilder builder = new StringBuilder(array.length * 7);
        builder.append(array[0]);
        for (int i = 1; i < array.length; i++)
        {
            builder.append(separator).append(array[i]);
        }
        return builder.toString();
    }

    /**
     * Returns a comparator that compares two {@code boolean} arrays <a
     * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>. That is, it
     * compares, using {@link #compare(boolean, boolean)}), the first pair of values that follow any
     * common prefix, or when one array is a prefix of the other, treats the shorter array as the
     * lesser. For example, {@code [] < [false] < [false, true] < [true]}.
     *
     * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
     * support only identity equality), but it is consistent with {@link Arrays#equals(boolean[],
     * boolean[])}.
     *
     * @since 2.0
     */
    public static Comparator<boolean[]> lexicographicalComparator()
    {
        return LexicographicalComparator.INSTANCE;
    }

    private enum LexicographicalComparator implements Comparator<boolean[]>
    {
        INSTANCE;

        @Override
        public int compare(boolean[] left, boolean[] right)
        {
            int minLength = Math.min(left.length, right.length);
            for (int i = 0; i < minLength; i++)
            {
                int result = Booleans.compare(left[i], right[i]);
                if (result != 0)
                {
                    return result;
                }
            }
            return left.length - right.length;
        }

        @Override
        public String toString()
        {
            return "Booleans.lexicographicalComparator()";
        }
    }

    /**
     * Copies a collection of {@code Boolean} instances into a new array of primitive {@code boolean}
     * values.
     *
     * <p>Elements are copied from the argument collection as if by {@code collection.toArray()}.
     * Calling this method is as thread-safe as calling that method.
     *
     * <p><b>Note:</b> consider representing the collection as a {@link java.util.BitSet} instead.
     *
     * @param collection a collection of {@code Boolean} objects
     * @return an array containing the same values as {@code collection}, in the same order, converted
     * to primitives
     * @throws NullPointerException if {@code collection} or any of its elements is null
     */
    public static boolean[] toArray(Collection<Boolean> collection)
    {
        if (collection instanceof BooleanArrayAsList)
        {
            return ((BooleanArrayAsList) collection).toBooleanArray();
        }

        Object[] boxedArray = collection.toArray();
        int len = boxedArray.length;
        boolean[] array = new boolean[len];
        for (int i = 0; i < len; i++)
        {
            // checkNotNull for GWT (do not optimize)
            array[i] = (Boolean) checkNotNull(boxedArray[i]);
        }
        return array;
    }

    /**
     * Returns a fixed-size list backed by the specified array, similar to {@link
     * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
     * set a value to {@code null} will result in a {@link NullPointerException}.
     *
     * <p>The returned list maintains the values, but not the identities, of {@code Boolean} objects
     * written to or read from it. For example, whether {@code list.get(0) == list.get(0)} is true for
     * the returned list is unspecified.
     *
     * @param backingArray the array to back the list
     * @return a list view of the array
     */
    public static List<Boolean> asList(boolean... backingArray)
    {
        if (backingArray.length == 0)
        {
            return Collections.emptyList();
        }
        return new BooleanArrayAsList(backingArray);
    }

    @GwtCompatible
    private static class BooleanArrayAsList extends AbstractList<Boolean>
            implements RandomAccess, Serializable
    {
        final boolean[] array;
        final int start;
        final int end;

        BooleanArrayAsList(boolean[] array)
        {
            this(array, 0, array.length);
        }

        BooleanArrayAsList(boolean[] array, int start, int end)
        {
            this.array = array;
            this.start = start;
            this.end = end;
        }

        @Override
        public int size()
        {
            return end - start;
        }

        @Override
        public boolean isEmpty()
        {
            return false;
        }

        @Override
        public Boolean get(int index)
        {
            checkElementIndex(index, size());
            return array[start + index];
        }

        @Override
        public boolean contains(@CheckForNull Object target)
        {
            // Overridden to prevent a ton of boxing
            return (target instanceof Boolean)
                    && Booleans.indexOf(array, (Boolean) target, start, end) != -1;
        }

        @Override
        public int indexOf(@CheckForNull Object target)
        {
            // Overridden to prevent a ton of boxing
            if (target instanceof Boolean)
            {
                int i = Booleans.indexOf(array, (Boolean) target, start, end);
                if (i >= 0)
                {
                    return i - start;
                }
            }
            return -1;
        }

        @Override
        public int lastIndexOf(@CheckForNull Object target)
        {
            // Overridden to prevent a ton of boxing
            if (target instanceof Boolean)
            {
                int i = Booleans.lastIndexOf(array, (Boolean) target, start, end);
                if (i >= 0)
                {
                    return i - start;
                }
            }
            return -1;
        }

        @Override
        public Boolean set(int index, Boolean element)
        {
            checkElementIndex(index, size());
            boolean oldValue = array[start + index];
            // checkNotNull for GWT (do not optimize)
            array[start + index] = checkNotNull(element);
            return oldValue;
        }

        @Override
        public List<Boolean> subList(int fromIndex, int toIndex)
        {
            int size = size();
            checkPositionIndexes(fromIndex, toIndex, size);
            if (fromIndex == toIndex)
            {
                return Collections.emptyList();
            }
            return new BooleanArrayAsList(array, start + fromIndex, start + toIndex);
        }

        @Override
        public boolean equals(@CheckForNull Object object)
        {
            if (object == this)
            {
                return true;
            }
            if (object instanceof BooleanArrayAsList)
            {
                BooleanArrayAsList that = (BooleanArrayAsList) object;
                int size = size();
                if (that.size() != size)
                {
                    return false;
                }
                for (int i = 0; i < size; i++)
                {
                    if (array[start + i] != that.array[that.start + i])
                    {
                        return false;
                    }
                }
                return true;
            }
            return super.equals(object);
        }

        @Override
        public int hashCode()
        {
            int result = 1;
            for (int i = start; i < end; i++)
            {
                result = 31 * result + Booleans.hashCode(array[i]);
            }
            return result;
        }

        @Override
        public String toString()
        {
            StringBuilder builder = new StringBuilder(size() * 7);
            builder.append(array[start] ? "[true" : "[false");
            for (int i = start + 1; i < end; i++)
            {
                builder.append(array[i] ? ", true" : ", false");
            }
            return builder.append(']').toString();
        }

        boolean[] toBooleanArray()
        {
            return Arrays.copyOfRange(array, start, end);
        }

        private static final long serialVersionUID = 0;
    }

    /**
     * Returns the number of {@code values} that are {@code true}.
     *
     * @since 16.0
     */
    @Beta
    public static int countTrue(boolean... values)
    {
        int count = 0;
        for (boolean value : values)
        {
            if (value)
            {
                count++;
            }
        }
        return count;
    }

    /**
     * Reverses the elements of {@code array}. This is equivalent to {@code
     * Collections.reverse(Booleans.asList(array))}, but is likely to be more efficient.
     *
     * @since 23.1
     */
    public static void reverse(boolean[] array)
    {
        checkNotNull(array);
        reverse(array, 0, array.length);
    }

    /**
     * Reverses the elements of {@code array} between {@code fromIndex} inclusive and {@code toIndex}
     * exclusive. This is equivalent to {@code
     * Collections.reverse(Booleans.asList(array).subList(fromIndex, toIndex))}, but is likely to be
     * more efficient.
     *
     * @throws IndexOutOfBoundsException if {@code fromIndex < 0}, {@code toIndex > array.length}, or
     *                                   {@code toIndex > fromIndex}
     * @since 23.1
     */
    public static void reverse(boolean[] array, int fromIndex, int toIndex)
    {
        checkNotNull(array);
        checkPositionIndexes(fromIndex, toIndex, array.length);
        for (int i = fromIndex, j = toIndex - 1; i < j; i++, j--)
        {
            boolean tmp = array[i];
            array[i] = array[j];
            array[j] = tmp;
        }
    }
}
